The membrane used for the membrane electrolysis of NaCl brine to produce NaOH, H.sub.2 and Cl.sub.2 usually has ion exchange properties so that water can permeate the membrane which permits migration of sodium through the membrane.
Owing to the ability of the membrane to transport water, problems may arise in connection with the sealing of the membrane electrolyzer. Particularly, care must be taken to prevent water from extruding outwardly through the edge of the membrane. In order to prevent this, the membrane must be compressed adjacent to the gasket. If rubber gaskets are used on both sides of the membrane, the pressure applied will cause said gaskets to expand parallel to the surface of the membrane and that movement will result in damage to or destruction of the membrane.